reftable/record.c

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 /* record.c - methods for different types of records. */
  10
  11 #include "record.h"
  12
  13 #include "system.h"
  14 #include "constants.h"
  15 #include "reftable-error.h"
  16 #include "basics.h"
  17
  18 static struct reftable_record_vtable *
  19 reftable_record_vtable(struct reftable_record *rec);
  20 static void *reftable_record_data(struct reftable_record *rec);
  21
  22 int get_var_int(uint64_t *dest, struct string_view *in)
  23 {
  24         int ptr = 0;
  25         uint64_t val;
  26
  27         if (in->len == 0)
  28                 return -1;
  29         val = in->buf[ptr] & 0x7f;
  30
  31         while (in->buf[ptr] & 0x80) {
  32                 ptr++;
  33                 if (ptr > in->len) {
  34                         return -1;
  35                 }
  36                 val = (val + 1) << 7 | (uint64_t)(in->buf[ptr] & 0x7f);
  37         }
  38
  39         *dest = val;
  40         return ptr + 1;
  41 }
  42
  43 int put_var_int(struct string_view *dest, uint64_t val)
  44 {
  45         uint8_t buf[10] = { 0 };
  46         int i = 9;
  47         int n = 0;
  48         buf[i] = (uint8_t)(val & 0x7f);
  49         i--;
  50         while (1) {
  51                 val >>= 7;
  52                 if (!val) {
  53                         break;
  54                 }
  55                 val--;
  56                 buf[i] = 0x80 | (uint8_t)(val & 0x7f);
  57                 i--;
  58         }
  59
  60         n = sizeof(buf) - i - 1;
  61         if (dest->len < n)
  62                 return -1;
  63         memcpy(dest->buf, &buf[i + 1], n);
  64         return n;
  65 }
  66
  67 int reftable_is_block_type(uint8_t typ)
  68 {
  69         switch (typ) {
  70         case BLOCK_TYPE_REF:
  71         case BLOCK_TYPE_LOG:
  72         case BLOCK_TYPE_OBJ:
  73         case BLOCK_TYPE_INDEX:
  74                 return 1;
  75         }
  76         return 0;
  77 }
  78
  79 const unsigned char *reftable_ref_record_val1(const struct reftable_ref_record *rec)
  80 {
  81         switch (rec->value_type) {
  82         case REFTABLE_REF_VAL1:
  83                 return rec->value.val1;
  84         case REFTABLE_REF_VAL2:
  85                 return rec->value.val2.value;
  86         default:
  87                 return NULL;
  88         }
  89 }
  90
  91 const unsigned char *reftable_ref_record_val2(const struct reftable_ref_record *rec)
  92 {
  93         switch (rec->value_type) {
  94         case REFTABLE_REF_VAL2:
  95                 return rec->value.val2.target_value;
  96         default:
  97                 return NULL;
  98         }
  99 }
 100
 101 static int decode_string(struct strbuf *dest, struct string_view in)
 102 {
 103         int start_len = in.len;
 104         uint64_t tsize = 0;
 105         int n = get_var_int(&tsize, &in);
 106         if (n <= 0)
 107                 return -1;
 108         string_view_consume(&in, n);
 109         if (in.len < tsize)
 110                 return -1;
 111
 112         strbuf_reset(dest);
 113         strbuf_add(dest, in.buf, tsize);
 114         string_view_consume(&in, tsize);
 115
 116         return start_len - in.len;
 117 }
 118
 119 static int encode_string(char *str, struct string_view s)
 120 {
 121         struct string_view start = s;
 122         int l = strlen(str);
 123         int n = put_var_int(&s, l);
 124         if (n < 0)
 125                 return -1;
 126         string_view_consume(&s, n);
 127         if (s.len < l)
 128                 return -1;
 129         memcpy(s.buf, str, l);
 130         string_view_consume(&s, l);
 131
 132         return start.len - s.len;
 133 }
 134
 135 int reftable_encode_key(int *restart, struct string_view dest,
 136                         struct strbuf prev_key, struct strbuf key,
 137                         uint8_t extra)
 138 {
 139         struct string_view start = dest;
 140         int prefix_len = common_prefix_size(&prev_key, &key);
 141         uint64_t suffix_len = key.len - prefix_len;
 142         int n = put_var_int(&dest, (uint64_t)prefix_len);
 143         if (n < 0)
 144                 return -1;
 145         string_view_consume(&dest, n);
 146
 147         *restart = (prefix_len == 0);
 148
 149         n = put_var_int(&dest, suffix_len << 3 | (uint64_t)extra);
 150         if (n < 0)
 151                 return -1;
 152         string_view_consume(&dest, n);
 153
 154         if (dest.len < suffix_len)
 155                 return -1;
 156         memcpy(dest.buf, key.buf + prefix_len, suffix_len);
 157         string_view_consume(&dest, suffix_len);
 158
 159         return start.len - dest.len;
 160 }
 161
 162 int reftable_decode_key(struct strbuf *key, uint8_t *extra,
 163                         struct strbuf last_key, struct string_view in)
 164 {
 165         int start_len = in.len;
 166         uint64_t prefix_len = 0;
 167         uint64_t suffix_len = 0;
 168         int n = get_var_int(&prefix_len, &in);
 169         if (n < 0)
 170                 return -1;
 171         string_view_consume(&in, n);
 172
 173         if (prefix_len > last_key.len)
 174                 return -1;
 175
 176         n = get_var_int(&suffix_len, &in);
 177         if (n <= 0)
 178                 return -1;
 179         string_view_consume(&in, n);
 180
 181         *extra = (uint8_t)(suffix_len & 0x7);
 182         suffix_len >>= 3;
 183
 184         if (in.len < suffix_len)
 185                 return -1;
 186
 187         strbuf_reset(key);
 188         strbuf_add(key, last_key.buf, prefix_len);
 189         strbuf_add(key, in.buf, suffix_len);
 190         string_view_consume(&in, suffix_len);
 191
 192         return start_len - in.len;
 193 }
 194
 195 static void reftable_ref_record_key(const void *r, struct strbuf *dest)
 196 {
 197         const struct reftable_ref_record *rec =
 198                 (const struct reftable_ref_record *)r;
 199         strbuf_reset(dest);
 200         strbuf_addstr(dest, rec->refname);
 201 }
 202
 203 static void reftable_ref_record_copy_from(void *rec, const void *src_rec,
 204                                           int hash_size)
 205 {
 206         struct reftable_ref_record *ref = rec;
 207         const struct reftable_ref_record *src = src_rec;
 208         assert(hash_size > 0);
 209
 210         /* This is simple and correct, but we could probably reuse the hash
 211          * fields. */
 212         reftable_ref_record_release(ref);
 213         if (src->refname) {
 214                 ref->refname = xstrdup(src->refname);
 215         }
 216         ref->update_index = src->update_index;
 217         ref->value_type = src->value_type;
 218         switch (src->value_type) {
 219         case REFTABLE_REF_DELETION:
 220                 break;
 221         case REFTABLE_REF_VAL1:
 222                 memcpy(ref->value.val1, src->value.val1, hash_size);
 223                 break;
 224         case REFTABLE_REF_VAL2:
 225                 memcpy(ref->value.val2.value, src->value.val2.value, hash_size);
 226                 memcpy(ref->value.val2.target_value,
 227                        src->value.val2.target_value, hash_size);
 228                 break;
 229         case REFTABLE_REF_SYMREF:
 230                 ref->value.symref = xstrdup(src->value.symref);
 231                 break;
 232         }
 233 }
 234
 235 static char hexdigit(int c)
 236 {
 237         if (c <= 9)
 238                 return '0' + c;
 239         return 'a' + (c - 10);
 240 }
 241
 242 static void hex_format(char *dest, const unsigned char *src, int hash_size)
 243 {
 244         assert(hash_size > 0);
 245         if (src) {
 246                 int i = 0;
 247                 for (i = 0; i < hash_size; i++) {
 248                         dest[2 * i] = hexdigit(src[i] >> 4);
 249                         dest[2 * i + 1] = hexdigit(src[i] & 0xf);
 250                 }
 251                 dest[2 * hash_size] = 0;
 252         }
 253 }
 254
 255 static void reftable_ref_record_print_sz(const struct reftable_ref_record *ref,
 256                                          int hash_size)
 257 {
 258         char hex[GIT_MAX_HEXSZ + 1] = { 0 }; /* BUG */
 259         printf("ref{%s(%" PRIu64 ") ", ref->refname, ref->update_index);
 260         switch (ref->value_type) {
 261         case REFTABLE_REF_SYMREF:
 262                 printf("=> %s", ref->value.symref);
 263                 break;
 264         case REFTABLE_REF_VAL2:
 265                 hex_format(hex, ref->value.val2.value, hash_size);
 266                 printf("val 2 %s", hex);
 267                 hex_format(hex, ref->value.val2.target_value,
 268                            hash_size);
 269                 printf("(T %s)", hex);
 270                 break;
 271         case REFTABLE_REF_VAL1:
 272                 hex_format(hex, ref->value.val1, hash_size);
 273                 printf("val 1 %s", hex);
 274                 break;
 275         case REFTABLE_REF_DELETION:
 276                 printf("delete");
 277                 break;
 278         }
 279         printf("}\n");
 280 }
 281
 282 void reftable_ref_record_print(const struct reftable_ref_record *ref,
 283                                uint32_t hash_id) {
 284         reftable_ref_record_print_sz(ref, hash_size(hash_id));
 285 }
 286
 287 static void reftable_ref_record_release_void(void *rec)
 288 {
 289         reftable_ref_record_release(rec);
 290 }
 291
 292 void reftable_ref_record_release(struct reftable_ref_record *ref)
 293 {
 294         switch (ref->value_type) {
 295         case REFTABLE_REF_SYMREF:
 296                 reftable_free(ref->value.symref);
 297                 break;
 298         case REFTABLE_REF_VAL2:
 299                 break;
 300         case REFTABLE_REF_VAL1:
 301                 break;
 302         case REFTABLE_REF_DELETION:
 303                 break;
 304         default:
 305                 abort();
 306         }
 307
 308         reftable_free(ref->refname);
 309         memset(ref, 0, sizeof(struct reftable_ref_record));
 310 }
 311
 312 static uint8_t reftable_ref_record_val_type(const void *rec)
 313 {
 314         const struct reftable_ref_record *r =
 315                 (const struct reftable_ref_record *)rec;
 316         return r->value_type;
 317 }
 318
 319 static int reftable_ref_record_encode(const void *rec, struct string_view s,
 320                                       int hash_size)
 321 {
 322         const struct reftable_ref_record *r =
 323                 (const struct reftable_ref_record *)rec;
 324         struct string_view start = s;
 325         int n = put_var_int(&s, r->update_index);
 326         assert(hash_size > 0);
 327         if (n < 0)
 328                 return -1;
 329         string_view_consume(&s, n);
 330
 331         switch (r->value_type) {
 332         case REFTABLE_REF_SYMREF:
 333                 n = encode_string(r->value.symref, s);
 334                 if (n < 0) {
 335                         return -1;
 336                 }
 337                 string_view_consume(&s, n);
 338                 break;
 339         case REFTABLE_REF_VAL2:
 340                 if (s.len < 2 * hash_size) {
 341                         return -1;
 342                 }
 343                 memcpy(s.buf, r->value.val2.value, hash_size);
 344                 string_view_consume(&s, hash_size);
 345                 memcpy(s.buf, r->value.val2.target_value, hash_size);
 346                 string_view_consume(&s, hash_size);
 347                 break;
 348         case REFTABLE_REF_VAL1:
 349                 if (s.len < hash_size) {
 350                         return -1;
 351                 }
 352                 memcpy(s.buf, r->value.val1, hash_size);
 353                 string_view_consume(&s, hash_size);
 354                 break;
 355         case REFTABLE_REF_DELETION:
 356                 break;
 357         default:
 358                 abort();
 359         }
 360
 361         return start.len - s.len;
 362 }
 363
 364 static int reftable_ref_record_decode(void *rec, struct strbuf key,
 365                                       uint8_t val_type, struct string_view in,
 366                                       int hash_size)
 367 {
 368         struct reftable_ref_record *r = rec;
 369         struct string_view start = in;
 370         uint64_t update_index = 0;
 371         int n = get_var_int(&update_index, &in);
 372         if (n < 0)
 373                 return n;
 374         string_view_consume(&in, n);
 375
 376         reftable_ref_record_release(r);
 377
 378         assert(hash_size > 0);
 379
 380         r->refname = reftable_realloc(r->refname, key.len + 1);
 381         memcpy(r->refname, key.buf, key.len);
 382         r->update_index = update_index;
 383         r->refname[key.len] = 0;
 384         r->value_type = val_type;
 385         switch (val_type) {
 386         case REFTABLE_REF_VAL1:
 387                 if (in.len < hash_size) {
 388                         return -1;
 389                 }
 390
 391                 memcpy(r->value.val1, in.buf, hash_size);
 392                 string_view_consume(&in, hash_size);
 393                 break;
 394
 395         case REFTABLE_REF_VAL2:
 396                 if (in.len < 2 * hash_size) {
 397                         return -1;
 398                 }
 399
 400                 memcpy(r->value.val2.value, in.buf, hash_size);
 401                 string_view_consume(&in, hash_size);
 402
 403                 memcpy(r->value.val2.target_value, in.buf, hash_size);
 404                 string_view_consume(&in, hash_size);
 405                 break;
 406
 407         case REFTABLE_REF_SYMREF: {
 408                 struct strbuf dest = STRBUF_INIT;
 409                 int n = decode_string(&dest, in);
 410                 if (n < 0) {
 411                         return -1;
 412                 }
 413                 string_view_consume(&in, n);
 414                 r->value.symref = dest.buf;
 415         } break;
 416
 417         case REFTABLE_REF_DELETION:
 418                 break;
 419         default:
 420                 abort();
 421                 break;
 422         }
 423
 424         return start.len - in.len;
 425 }
 426
 427 static int reftable_ref_record_is_deletion_void(const void *p)
 428 {
 429         return reftable_ref_record_is_deletion(
 430                 (const struct reftable_ref_record *)p);
 431 }
 432
 433
 434 static int reftable_ref_record_equal_void(const void *a,
 435                                           const void *b, int hash_size)
 436 {
 437         struct reftable_ref_record *ra = (struct reftable_ref_record *) a;
 438         struct reftable_ref_record *rb = (struct reftable_ref_record *) b;
 439         return reftable_ref_record_equal(ra, rb, hash_size);
 440 }
 441
 442 static void reftable_ref_record_print_void(const void *rec,
 443                                            int hash_size)
 444 {
 445         reftable_ref_record_print_sz((struct reftable_ref_record *) rec, hash_size);
 446 }
 447
 448 static struct reftable_record_vtable reftable_ref_record_vtable = {
 449         .key = &reftable_ref_record_key,
 450         .type = BLOCK_TYPE_REF,
 451         .copy_from = &reftable_ref_record_copy_from,
 452         .val_type = &reftable_ref_record_val_type,
 453         .encode = &reftable_ref_record_encode,
 454         .decode = &reftable_ref_record_decode,
 455         .release = &reftable_ref_record_release_void,
 456         .is_deletion = &reftable_ref_record_is_deletion_void,
 457         .equal = &reftable_ref_record_equal_void,
 458         .print = &reftable_ref_record_print_void,
 459 };
 460
 461 static void reftable_obj_record_key(const void *r, struct strbuf *dest)
 462 {
 463         const struct reftable_obj_record *rec =
 464                 (const struct reftable_obj_record *)r;
 465         strbuf_reset(dest);
 466         strbuf_add(dest, rec->hash_prefix, rec->hash_prefix_len);
 467 }
 468
 469 static void reftable_obj_record_release(void *rec)
 470 {
 471         struct reftable_obj_record *obj = rec;
 472         FREE_AND_NULL(obj->hash_prefix);
 473         FREE_AND_NULL(obj->offsets);
 474         memset(obj, 0, sizeof(struct reftable_obj_record));
 475 }
 476
 477 static void reftable_obj_record_print(const void *rec, int hash_size)
 478 {
 479         const struct reftable_obj_record *obj = rec;
 480         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 481         struct strbuf offset_str = STRBUF_INIT;
 482         int i;
 483
 484         for (i = 0; i < obj->offset_len; i++)
 485                 strbuf_addf(&offset_str, "%" PRIu64 " ", obj->offsets[i]);
 486         hex_format(hex, obj->hash_prefix, obj->hash_prefix_len);
 487         printf("prefix %s (len %d), offsets [%s]\n",
 488                hex, obj->hash_prefix_len, offset_str.buf);
 489         strbuf_release(&offset_str);
 490 }
 491
 492 static void reftable_obj_record_copy_from(void *rec, const void *src_rec,
 493                                           int hash_size)
 494 {
 495         struct reftable_obj_record *obj = rec;
 496         const struct reftable_obj_record *src =
 497                 (const struct reftable_obj_record *)src_rec;
 498
 499         reftable_obj_record_release(obj);
 500
 501         REFTABLE_ALLOC_ARRAY(obj->hash_prefix, src->hash_prefix_len);
 502         obj->hash_prefix_len = src->hash_prefix_len;
 503         if (src->hash_prefix_len)
 504                 memcpy(obj->hash_prefix, src->hash_prefix, obj->hash_prefix_len);
 505
 506         REFTABLE_ALLOC_ARRAY(obj->offsets, src->offset_len);
 507         obj->offset_len = src->offset_len;
 508         COPY_ARRAY(obj->offsets, src->offsets, src->offset_len);
 509 }
 510
 511 static uint8_t reftable_obj_record_val_type(const void *rec)
 512 {
 513         const struct reftable_obj_record *r = rec;
 514         if (r->offset_len > 0 && r->offset_len < 8)
 515                 return r->offset_len;
 516         return 0;
 517 }
 518
 519 static int reftable_obj_record_encode(const void *rec, struct string_view s,
 520                                       int hash_size)
 521 {
 522         const struct reftable_obj_record *r = rec;
 523         struct string_view start = s;
 524         int i = 0;
 525         int n = 0;
 526         uint64_t last = 0;
 527         if (r->offset_len == 0 || r->offset_len >= 8) {
 528                 n = put_var_int(&s, r->offset_len);
 529                 if (n < 0) {
 530                         return -1;
 531                 }
 532                 string_view_consume(&s, n);
 533         }
 534         if (r->offset_len == 0)
 535                 return start.len - s.len;
 536         n = put_var_int(&s, r->offsets[0]);
 537         if (n < 0)
 538                 return -1;
 539         string_view_consume(&s, n);
 540
 541         last = r->offsets[0];
 542         for (i = 1; i < r->offset_len; i++) {
 543                 int n = put_var_int(&s, r->offsets[i] - last);
 544                 if (n < 0) {
 545                         return -1;
 546                 }
 547                 string_view_consume(&s, n);
 548                 last = r->offsets[i];
 549         }
 550         return start.len - s.len;
 551 }
 552
 553 static int reftable_obj_record_decode(void *rec, struct strbuf key,
 554                                       uint8_t val_type, struct string_view in,
 555                                       int hash_size)
 556 {
 557         struct string_view start = in;
 558         struct reftable_obj_record *r = rec;
 559         uint64_t count = val_type;
 560         int n = 0;
 561         uint64_t last;
 562         int j;
 563
 564         REFTABLE_ALLOC_ARRAY(r->hash_prefix, key.len);
 565         memcpy(r->hash_prefix, key.buf, key.len);
 566         r->hash_prefix_len = key.len;
 567
 568         if (val_type == 0) {
 569                 n = get_var_int(&count, &in);
 570                 if (n < 0) {
 571                         return n;
 572                 }
 573
 574                 string_view_consume(&in, n);
 575         }
 576
 577         r->offsets = NULL;
 578         r->offset_len = 0;
 579         if (count == 0)
 580                 return start.len - in.len;
 581
 582         REFTABLE_ALLOC_ARRAY(r->offsets, count);
 583         r->offset_len = count;
 584
 585         n = get_var_int(&r->offsets[0], &in);
 586         if (n < 0)
 587                 return n;
 588         string_view_consume(&in, n);
 589
 590         last = r->offsets[0];
 591         j = 1;
 592         while (j < count) {
 593                 uint64_t delta = 0;
 594                 int n = get_var_int(&delta, &in);
 595                 if (n < 0) {
 596                         return n;
 597                 }
 598                 string_view_consume(&in, n);
 599
 600                 last = r->offsets[j] = (delta + last);
 601                 j++;
 602         }
 603         return start.len - in.len;
 604 }
 605
 606 static int not_a_deletion(const void *p)
 607 {
 608         return 0;
 609 }
 610
 611 static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
 612 {
 613         struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 614         struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
 615
 616         if (ra->hash_prefix_len != rb->hash_prefix_len
 617             || ra->offset_len != rb->offset_len)
 618                 return 0;
 619
 620         if (ra->hash_prefix_len &&
 621             memcmp(ra->hash_prefix, rb->hash_prefix, ra->hash_prefix_len))
 622                 return 0;
 623         if (ra->offset_len &&
 624             memcmp(ra->offsets, rb->offsets, ra->offset_len * sizeof(uint64_t)))
 625                 return 0;
 626
 627         return 1;
 628 }
 629
 630 static struct reftable_record_vtable reftable_obj_record_vtable = {
 631         .key = &reftable_obj_record_key,
 632         .type = BLOCK_TYPE_OBJ,
 633         .copy_from = &reftable_obj_record_copy_from,
 634         .val_type = &reftable_obj_record_val_type,
 635         .encode = &reftable_obj_record_encode,
 636         .decode = &reftable_obj_record_decode,
 637         .release = &reftable_obj_record_release,
 638         .is_deletion = &not_a_deletion,
 639         .equal = &reftable_obj_record_equal_void,
 640         .print = &reftable_obj_record_print,
 641 };
 642
 643 static void reftable_log_record_print_sz(struct reftable_log_record *log,
 644                                          int hash_size)
 645 {
 646         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 647
 648         switch (log->value_type) {
 649         case REFTABLE_LOG_DELETION:
 650                 printf("log{%s(%" PRIu64 ") delete\n", log->refname,
 651                        log->update_index);
 652                 break;
 653         case REFTABLE_LOG_UPDATE:
 654                 printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
 655                        log->refname, log->update_index,
 656                        log->value.update.name ? log->value.update.name : "",
 657                        log->value.update.email ? log->value.update.email : "",
 658                        log->value.update.time,
 659                        log->value.update.tz_offset);
 660                 hex_format(hex, log->value.update.old_hash, hash_size);
 661                 printf("%s => ", hex);
 662                 hex_format(hex, log->value.update.new_hash, hash_size);
 663                 printf("%s\n\n%s\n}\n", hex,
 664                        log->value.update.message ? log->value.update.message : "");
 665                 break;
 666         }
 667 }
 668
 669 void reftable_log_record_print(struct reftable_log_record *log,
 670                                       uint32_t hash_id)
 671 {
 672         reftable_log_record_print_sz(log, hash_size(hash_id));
 673 }
 674
 675 static void reftable_log_record_key(const void *r, struct strbuf *dest)
 676 {
 677         const struct reftable_log_record *rec =
 678                 (const struct reftable_log_record *)r;
 679         int len = strlen(rec->refname);
 680         uint8_t i64[8];
 681         uint64_t ts = 0;
 682         strbuf_reset(dest);
 683         strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
 684
 685         ts = (~ts) - rec->update_index;
 686         put_be64(&i64[0], ts);
 687         strbuf_add(dest, i64, sizeof(i64));
 688 }
 689
 690 static void reftable_log_record_copy_from(void *rec, const void *src_rec,
 691                                           int hash_size)
 692 {
 693         struct reftable_log_record *dst = rec;
 694         const struct reftable_log_record *src =
 695                 (const struct reftable_log_record *)src_rec;
 696
 697         reftable_log_record_release(dst);
 698         *dst = *src;
 699         if (dst->refname) {
 700                 dst->refname = xstrdup(dst->refname);
 701         }
 702         switch (dst->value_type) {
 703         case REFTABLE_LOG_DELETION:
 704                 break;
 705         case REFTABLE_LOG_UPDATE:
 706                 if (dst->value.update.email) {
 707                         dst->value.update.email =
 708                                 xstrdup(dst->value.update.email);
 709                 }
 710                 if (dst->value.update.name) {
 711                         dst->value.update.name =
 712                                 xstrdup(dst->value.update.name);
 713                 }
 714                 if (dst->value.update.message) {
 715                         dst->value.update.message =
 716                                 xstrdup(dst->value.update.message);
 717                 }
 718
 719                 if (dst->value.update.new_hash) {
 720                         REFTABLE_ALLOC_ARRAY(dst->value.update.new_hash, hash_size);
 721                         memcpy(dst->value.update.new_hash,
 722                                src->value.update.new_hash, hash_size);
 723                 }
 724                 if (dst->value.update.old_hash) {
 725                         REFTABLE_ALLOC_ARRAY(dst->value.update.old_hash, hash_size);
 726                         memcpy(dst->value.update.old_hash,
 727                                src->value.update.old_hash, hash_size);
 728                 }
 729                 break;
 730         }
 731 }
 732
 733 static void reftable_log_record_release_void(void *rec)
 734 {
 735         struct reftable_log_record *r = rec;
 736         reftable_log_record_release(r);
 737 }
 738
 739 void reftable_log_record_release(struct reftable_log_record *r)
 740 {
 741         reftable_free(r->refname);
 742         switch (r->value_type) {
 743         case REFTABLE_LOG_DELETION:
 744                 break;
 745         case REFTABLE_LOG_UPDATE:
 746                 reftable_free(r->value.update.new_hash);
 747                 reftable_free(r->value.update.old_hash);
 748                 reftable_free(r->value.update.name);
 749                 reftable_free(r->value.update.email);
 750                 reftable_free(r->value.update.message);
 751                 break;
 752         }
 753         memset(r, 0, sizeof(struct reftable_log_record));
 754 }
 755
 756 static uint8_t reftable_log_record_val_type(const void *rec)
 757 {
 758         const struct reftable_log_record *log =
 759                 (const struct reftable_log_record *)rec;
 760
 761         return reftable_log_record_is_deletion(log) ? 0 : 1;
 762 }
 763
 764 static uint8_t zero[GIT_SHA256_RAWSZ] = { 0 };
 765
 766 static int reftable_log_record_encode(const void *rec, struct string_view s,
 767                                       int hash_size)
 768 {
 769         const struct reftable_log_record *r = rec;
 770         struct string_view start = s;
 771         int n = 0;
 772         uint8_t *oldh = NULL;
 773         uint8_t *newh = NULL;
 774         if (reftable_log_record_is_deletion(r))
 775                 return 0;
 776
 777         oldh = r->value.update.old_hash;
 778         newh = r->value.update.new_hash;
 779         if (!oldh) {
 780                 oldh = zero;
 781         }
 782         if (!newh) {
 783                 newh = zero;
 784         }
 785
 786         if (s.len < 2 * hash_size)
 787                 return -1;
 788
 789         memcpy(s.buf, oldh, hash_size);
 790         memcpy(s.buf + hash_size, newh, hash_size);
 791         string_view_consume(&s, 2 * hash_size);
 792
 793         n = encode_string(r->value.update.name ? r->value.update.name : "", s);
 794         if (n < 0)
 795                 return -1;
 796         string_view_consume(&s, n);
 797
 798         n = encode_string(r->value.update.email ? r->value.update.email : "",
 799                           s);
 800         if (n < 0)
 801                 return -1;
 802         string_view_consume(&s, n);
 803
 804         n = put_var_int(&s, r->value.update.time);
 805         if (n < 0)
 806                 return -1;
 807         string_view_consume(&s, n);
 808
 809         if (s.len < 2)
 810                 return -1;
 811
 812         put_be16(s.buf, r->value.update.tz_offset);
 813         string_view_consume(&s, 2);
 814
 815         n = encode_string(
 816                 r->value.update.message ? r->value.update.message : "", s);
 817         if (n < 0)
 818                 return -1;
 819         string_view_consume(&s, n);
 820
 821         return start.len - s.len;
 822 }
 823
 824 static int reftable_log_record_decode(void *rec, struct strbuf key,
 825                                       uint8_t val_type, struct string_view in,
 826                                       int hash_size)
 827 {
 828         struct string_view start = in;
 829         struct reftable_log_record *r = rec;
 830         uint64_t max = 0;
 831         uint64_t ts = 0;
 832         struct strbuf dest = STRBUF_INIT;
 833         int n;
 834
 835         if (key.len <= 9 || key.buf[key.len - 9] != 0)
 836                 return REFTABLE_FORMAT_ERROR;
 837
 838         r->refname = reftable_realloc(r->refname, key.len - 8);
 839         memcpy(r->refname, key.buf, key.len - 8);
 840         ts = get_be64(key.buf + key.len - 8);
 841
 842         r->update_index = (~max) - ts;
 843
 844         if (val_type != r->value_type) {
 845                 switch (r->value_type) {
 846                 case REFTABLE_LOG_UPDATE:
 847                         FREE_AND_NULL(r->value.update.old_hash);
 848                         FREE_AND_NULL(r->value.update.new_hash);
 849                         FREE_AND_NULL(r->value.update.message);
 850                         FREE_AND_NULL(r->value.update.email);
 851                         FREE_AND_NULL(r->value.update.name);
 852                         break;
 853                 case REFTABLE_LOG_DELETION:
 854                         break;
 855                 }
 856         }
 857
 858         r->value_type = val_type;
 859         if (val_type == REFTABLE_LOG_DELETION)
 860                 return 0;
 861
 862         if (in.len < 2 * hash_size)
 863                 return REFTABLE_FORMAT_ERROR;
 864
 865         r->value.update.old_hash =
 866                 reftable_realloc(r->value.update.old_hash, hash_size);
 867         r->value.update.new_hash =
 868                 reftable_realloc(r->value.update.new_hash, hash_size);
 869
 870         memcpy(r->value.update.old_hash, in.buf, hash_size);
 871         memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
 872
 873         string_view_consume(&in, 2 * hash_size);
 874
 875         n = decode_string(&dest, in);
 876         if (n < 0)
 877                 goto done;
 878         string_view_consume(&in, n);
 879
 880         r->value.update.name =
 881                 reftable_realloc(r->value.update.name, dest.len + 1);
 882         memcpy(r->value.update.name, dest.buf, dest.len);
 883         r->value.update.name[dest.len] = 0;
 884
 885         strbuf_reset(&dest);
 886         n = decode_string(&dest, in);
 887         if (n < 0)
 888                 goto done;
 889         string_view_consume(&in, n);
 890
 891         r->value.update.email =
 892                 reftable_realloc(r->value.update.email, dest.len + 1);
 893         memcpy(r->value.update.email, dest.buf, dest.len);
 894         r->value.update.email[dest.len] = 0;
 895
 896         ts = 0;
 897         n = get_var_int(&ts, &in);
 898         if (n < 0)
 899                 goto done;
 900         string_view_consume(&in, n);
 901         r->value.update.time = ts;
 902         if (in.len < 2)
 903                 goto done;
 904
 905         r->value.update.tz_offset = get_be16(in.buf);
 906         string_view_consume(&in, 2);
 907
 908         strbuf_reset(&dest);
 909         n = decode_string(&dest, in);
 910         if (n < 0)
 911                 goto done;
 912         string_view_consume(&in, n);
 913
 914         r->value.update.message =
 915                 reftable_realloc(r->value.update.message, dest.len + 1);
 916         memcpy(r->value.update.message, dest.buf, dest.len);
 917         r->value.update.message[dest.len] = 0;
 918
 919         strbuf_release(&dest);
 920         return start.len - in.len;
 921
 922 done:
 923         strbuf_release(&dest);
 924         return REFTABLE_FORMAT_ERROR;
 925 }
 926
 927 static int null_streq(char *a, char *b)
 928 {
 929         char *empty = "";
 930         if (!a)
 931                 a = empty;
 932
 933         if (!b)
 934                 b = empty;
 935
 936         return 0 == strcmp(a, b);
 937 }
 938
 939 static int zero_hash_eq(uint8_t *a, uint8_t *b, int sz)
 940 {
 941         if (!a)
 942                 a = zero;
 943
 944         if (!b)
 945                 b = zero;
 946
 947         return !memcmp(a, b, sz);
 948 }
 949
 950 static int reftable_log_record_equal_void(const void *a,
 951                                           const void *b, int hash_size)
 952 {
 953         return reftable_log_record_equal((struct reftable_log_record *) a,
 954                                          (struct reftable_log_record *) b,
 955                                          hash_size);
 956 }
 957
 958 int reftable_log_record_equal(const struct reftable_log_record *a,
 959                               const struct reftable_log_record *b, int hash_size)
 960 {
 961         if (!(null_streq(a->refname, b->refname) &&
 962               a->update_index == b->update_index &&
 963               a->value_type == b->value_type))
 964                 return 0;
 965
 966         switch (a->value_type) {
 967         case REFTABLE_LOG_DELETION:
 968                 return 1;
 969         case REFTABLE_LOG_UPDATE:
 970                 return null_streq(a->value.update.name, b->value.update.name) &&
 971                        a->value.update.time == b->value.update.time &&
 972                        a->value.update.tz_offset == b->value.update.tz_offset &&
 973                        null_streq(a->value.update.email,
 974                                   b->value.update.email) &&
 975                        null_streq(a->value.update.message,
 976                                   b->value.update.message) &&
 977                        zero_hash_eq(a->value.update.old_hash,
 978                                     b->value.update.old_hash, hash_size) &&
 979                        zero_hash_eq(a->value.update.new_hash,
 980                                     b->value.update.new_hash, hash_size);
 981         }
 982
 983         abort();
 984 }
 985
 986 static int reftable_log_record_is_deletion_void(const void *p)
 987 {
 988         return reftable_log_record_is_deletion(
 989                 (const struct reftable_log_record *)p);
 990 }
 991
 992 static void reftable_log_record_print_void(const void *rec, int hash_size)
 993 {
 994         reftable_log_record_print_sz((struct reftable_log_record*)rec, hash_size);
 995 }
 996
 997 static struct reftable_record_vtable reftable_log_record_vtable = {
 998         .key = &reftable_log_record_key,
 999         .type = BLOCK_TYPE_LOG,
1000         .copy_from = &reftable_log_record_copy_from,
1001         .val_type = &reftable_log_record_val_type,
1002         .encode = &reftable_log_record_encode,
1003         .decode = &reftable_log_record_decode,
1004         .release = &reftable_log_record_release_void,
1005         .is_deletion = &reftable_log_record_is_deletion_void,
1006         .equal = &reftable_log_record_equal_void,
1007         .print = &reftable_log_record_print_void,
1008 };
1009
1010 static void reftable_index_record_key(const void *r, struct strbuf *dest)
1011 {
1012         const struct reftable_index_record *rec = r;
1013         strbuf_reset(dest);
1014         strbuf_addbuf(dest, &rec->last_key);
1015 }
1016
1017 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
1018                                             int hash_size)
1019 {
1020         struct reftable_index_record *dst = rec;
1021         const struct reftable_index_record *src = src_rec;
1022
1023         strbuf_reset(&dst->last_key);
1024         strbuf_addbuf(&dst->last_key, &src->last_key);
1025         dst->offset = src->offset;
1026 }
1027
1028 static void reftable_index_record_release(void *rec)
1029 {
1030         struct reftable_index_record *idx = rec;
1031         strbuf_release(&idx->last_key);
1032 }
1033
1034 static uint8_t reftable_index_record_val_type(const void *rec)
1035 {
1036         return 0;
1037 }
1038
1039 static int reftable_index_record_encode(const void *rec, struct string_view out,
1040                                         int hash_size)
1041 {
1042         const struct reftable_index_record *r =
1043                 (const struct reftable_index_record *)rec;
1044         struct string_view start = out;
1045
1046         int n = put_var_int(&out, r->offset);
1047         if (n < 0)
1048                 return n;
1049
1050         string_view_consume(&out, n);
1051
1052         return start.len - out.len;
1053 }
1054
1055 static int reftable_index_record_decode(void *rec, struct strbuf key,
1056                                         uint8_t val_type, struct string_view in,
1057                                         int hash_size)
1058 {
1059         struct string_view start = in;
1060         struct reftable_index_record *r = rec;
1061         int n = 0;
1062
1063         strbuf_reset(&r->last_key);
1064         strbuf_addbuf(&r->last_key, &key);
1065
1066         n = get_var_int(&r->offset, &in);
1067         if (n < 0)
1068                 return n;
1069
1070         string_view_consume(&in, n);
1071         return start.len - in.len;
1072 }
1073
1074 static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
1075 {
1076         struct reftable_index_record *ia = (struct reftable_index_record *) a;
1077         struct reftable_index_record *ib = (struct reftable_index_record *) b;
1078
1079         return ia->offset == ib->offset && !strbuf_cmp(&ia->last_key, &ib->last_key);
1080 }
1081
1082 static void reftable_index_record_print(const void *rec, int hash_size)
1083 {
1084         const struct reftable_index_record *idx = rec;
1085         /* TODO: escape null chars? */
1086         printf("\"%s\" %" PRIu64 "\n", idx->last_key.buf, idx->offset);
1087 }
1088
1089 static struct reftable_record_vtable reftable_index_record_vtable = {
1090         .key = &reftable_index_record_key,
1091         .type = BLOCK_TYPE_INDEX,
1092         .copy_from = &reftable_index_record_copy_from,
1093         .val_type = &reftable_index_record_val_type,
1094         .encode = &reftable_index_record_encode,
1095         .decode = &reftable_index_record_decode,
1096         .release = &reftable_index_record_release,
1097         .is_deletion = &not_a_deletion,
1098         .equal = &reftable_index_record_equal,
1099         .print = &reftable_index_record_print,
1100 };
1101
1102 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
1103 {
1104         reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
1105 }
1106
1107 uint8_t reftable_record_type(struct reftable_record *rec)
1108 {
1109         return rec->type;
1110 }
1111
1112 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
1113                            int hash_size)
1114 {
1115         return reftable_record_vtable(rec)->encode(reftable_record_data(rec),
1116                                                    dest, hash_size);
1117 }
1118
1119 void reftable_record_copy_from(struct reftable_record *rec,
1120                                struct reftable_record *src, int hash_size)
1121 {
1122         assert(src->type == rec->type);
1123
1124         reftable_record_vtable(rec)->copy_from(reftable_record_data(rec),
1125                                                reftable_record_data(src),
1126                                                hash_size);
1127 }
1128
1129 uint8_t reftable_record_val_type(struct reftable_record *rec)
1130 {
1131         return reftable_record_vtable(rec)->val_type(reftable_record_data(rec));
1132 }
1133
1134 int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
1135                            uint8_t extra, struct string_view src, int hash_size)
1136 {
1137         return reftable_record_vtable(rec)->decode(reftable_record_data(rec),
1138                                                    key, extra, src, hash_size);
1139 }
1140
1141 void reftable_record_release(struct reftable_record *rec)
1142 {
1143         reftable_record_vtable(rec)->release(reftable_record_data(rec));
1144 }
1145
1146 int reftable_record_is_deletion(struct reftable_record *rec)
1147 {
1148         return reftable_record_vtable(rec)->is_deletion(
1149                 reftable_record_data(rec));
1150 }
1151
1152 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size)
1153 {
1154         if (a->type != b->type)
1155                 return 0;
1156         return reftable_record_vtable(a)->equal(
1157                 reftable_record_data(a), reftable_record_data(b), hash_size);
1158 }
1159
1160 static int hash_equal(const unsigned char *a, const unsigned char *b, int hash_size)
1161 {
1162         if (a && b)
1163                 return !memcmp(a, b, hash_size);
1164
1165         return a == b;
1166 }
1167
1168 int reftable_ref_record_equal(const struct reftable_ref_record *a,
1169                               const struct reftable_ref_record *b, int hash_size)
1170 {
1171         assert(hash_size > 0);
1172         if (!null_streq(a->refname, b->refname))
1173                 return 0;
1174
1175         if (a->update_index != b->update_index ||
1176             a->value_type != b->value_type)
1177                 return 0;
1178
1179         switch (a->value_type) {
1180         case REFTABLE_REF_SYMREF:
1181                 return !strcmp(a->value.symref, b->value.symref);
1182         case REFTABLE_REF_VAL2:
1183                 return hash_equal(a->value.val2.value, b->value.val2.value,
1184                                   hash_size) &&
1185                        hash_equal(a->value.val2.target_value,
1186                                   b->value.val2.target_value, hash_size);
1187         case REFTABLE_REF_VAL1:
1188                 return hash_equal(a->value.val1, b->value.val1, hash_size);
1189         case REFTABLE_REF_DELETION:
1190                 return 1;
1191         default:
1192                 abort();
1193         }
1194 }
1195
1196 int reftable_ref_record_compare_name(const void *a, const void *b)
1197 {
1198         return strcmp(((struct reftable_ref_record *)a)->refname,
1199                       ((struct reftable_ref_record *)b)->refname);
1200 }
1201
1202 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
1203 {
1204         return ref->value_type == REFTABLE_REF_DELETION;
1205 }
1206
1207 int reftable_log_record_compare_key(const void *a, const void *b)
1208 {
1209         const struct reftable_log_record *la = a;
1210         const struct reftable_log_record *lb = b;
1211
1212         int cmp = strcmp(la->refname, lb->refname);
1213         if (cmp)
1214                 return cmp;
1215         if (la->update_index > lb->update_index)
1216                 return -1;
1217         return (la->update_index < lb->update_index) ? 1 : 0;
1218 }
1219
1220 int reftable_log_record_is_deletion(const struct reftable_log_record *log)
1221 {
1222         return (log->value_type == REFTABLE_LOG_DELETION);
1223 }
1224
1225 void string_view_consume(struct string_view *s, int n)
1226 {
1227         s->buf += n;
1228         s->len -= n;
1229 }
1230
1231 static void *reftable_record_data(struct reftable_record *rec)
1232 {
1233         switch (rec->type) {
1234         case BLOCK_TYPE_REF:
1235                 return &rec->u.ref;
1236         case BLOCK_TYPE_LOG:
1237                 return &rec->u.log;
1238         case BLOCK_TYPE_INDEX:
1239                 return &rec->u.idx;
1240         case BLOCK_TYPE_OBJ:
1241                 return &rec->u.obj;
1242         }
1243         abort();
1244 }
1245
1246 static struct reftable_record_vtable *
1247 reftable_record_vtable(struct reftable_record *rec)
1248 {
1249         switch (rec->type) {
1250         case BLOCK_TYPE_REF:
1251                 return &reftable_ref_record_vtable;
1252         case BLOCK_TYPE_LOG:
1253                 return &reftable_log_record_vtable;
1254         case BLOCK_TYPE_INDEX:
1255                 return &reftable_index_record_vtable;
1256         case BLOCK_TYPE_OBJ:
1257                 return &reftable_obj_record_vtable;
1258         }
1259         abort();
1260 }
1261
1262 void reftable_record_init(struct reftable_record *rec, uint8_t typ)
1263 {
1264         memset(rec, 0, sizeof(*rec));
1265         rec->type = typ;
1266
1267         switch (typ) {
1268         case BLOCK_TYPE_REF:
1269         case BLOCK_TYPE_LOG:
1270         case BLOCK_TYPE_OBJ:
1271                 return;
1272         case BLOCK_TYPE_INDEX:
1273                 strbuf_init(&rec->u.idx.last_key, 0);
1274                 return;
1275         default:
1276                 BUG("unhandled record type");
1277         }
1278 }
1279
1280 void reftable_record_print(struct reftable_record *rec, int hash_size)
1281 {
1282         printf("'%c': ", rec->type);
1283         reftable_record_vtable(rec)->print(reftable_record_data(rec), hash_size);
1284 }